本省北部陽明山、內湖地區相思樹人工林放任後自然演替之研究

The Research of Natural Succession of Acacia confusa man-made Forest at Yang-Ming Mt. and Neihu Areas

徐寶琛(Pao-Chen Hsu)

《華岡農科學報》 19期 (2007/06) Pp. 67-80

https://doi.org/10.29985/HKJA.200706.0005

摘要

本研究由北部陽明山、內湖等地區海拔200~300多公尺之相思樹(Acacia confuse Merr.)人工林在放任而未再受干擾的7個均質次生林之植群分析以了解目前及推測未來自然演替後之植被結構變遷。相思樹是本省早期爲提供薪炭材而成爲低海拔重要造林樹種。後因薪炭材需求降低，相思樹人工林不再撫育，放任而成今日的次生林。本研究在陽明山、內湖等地區選擇放任後未再受農墾干擾且均質的次生林7個。各次生林取樣在要求變異度均小於0.18以下，每次生林必取25個小樣區。每個小樣區面積10×10平方公尺，25個小樣區共計2500平方公尺。7個次生林分別就25小樣區經每木調查、植群分析所得Simpson's歧異度指數、重要值指數(IVI)及重要優勢植物之胸徑級與株數關係圖後經過比較得知目前7個次生林，構成最上冠層的主要樹種均是胸徑20~65cm之相思樹，但在目前林內缺乏相思樹的中、小徑木，未來將無法更新而逐漸衰退；在未來不受干擾的自然演替下，林內相對密度及相對頻度高之陰性原生植物，如上中層的樹杞(Ardisia sieboldii)、江某(Scheffera octophylla)、山紅柿(Diospyro morrisiana)、紅楠(Machilus thunbergii)、大葉楠(Machilus kusanoi)，中下層之九節木(psychotria rubra)、燈稱花(Ilex asprella)等會成優勢種，而逐漸取代相思林。再藉Jaccard相似度指數及IVI勢植物序位比較，由“質”與“量”分析，預測7個次生林未來將成以陰吐原生植物爲主之3型均餓自物仕會。

關鍵字

相思樹 ； 次生林 ； 自然演替 ； 均質原生植物社會

並列摘要

This study is to research the change of vegetation structure by natural succession of manmade forest of Acacia confuse Merr. of 7 sites at Yang-Ming Mt. and Neihu areas. Acacia confusa is good raw material for man-made coal, so A. confusa was an important reforested species at low elevation in Taiwan early time. Since the need of man-made coal was decreased gradually, the A. confusa forest have become secondary forest because without tending and through autogenic succession for about more than 30 years later. This research is to select 7 site of homogenous secondany forest. Then sampling 25 plots at every site. The size of every plot is 10×10 m^2, 25 plots is 2500 m^2. Through vegetation analysis of every 25 plots can get Simpson's index of diversity, IVI (important value index), and the diagram of the relationsphip of every D.B.H. level and it's amount of 3~5 dominant species of very site. Then to compare the Jaccard similarity index of flora and it's sequence of 10 dominant species of IVI of 7 site. The conclusion of this research: At present the main species of the highest canopy of 7 secondary forest are Acacia confusa that D.B.H. about 20~65 cm, but no sapling; on the other hand, the shade native species of Ardisia sieboidii, Scheffiera octophylla, Diospyros morrisiana, Machilus thunbergii, Machilus kusanoi, Psychotria rubra, hex asprella etc. all have lots of sapling and seedling, so they are potential and will be dominant to replace Acacia confusa slowly, and will be three type of homogenous phytosocial of native species in the future through natural succession.

並列關鍵字

Acacia confusa Merr. ； secondary forest ； natural succession ； homogenous phytosocial of native species